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T 1852/13 - An End to the ‘Essentiality Test’?

OVERVIEW

In T 1852/13, the so-called ‘essentiality test’ was analysed in detail. Questions were raised as to whether this test is in compliance with the Gold Standard for assessing added subject-matter following claim amendments.

Background

The EPO's Boards of Appeal have previously used the 'essentiality test' to
determine whether after the deletion of a claim feature the remaining
subject-matter is still in compliance with the content disclosed in the
application-as-filed.

The essentiality test states that the removal or replacement of a feature
is not to be considered added subject-matter if it satisfies three
criteria:

the feature is not described as essential in the application-as-filed;

the feature is not,
as such, indispensable to the function of the invention in light of the
objective technical problem solved; and

the removal or
replacement of the feature requires no real modification of other features
to compensate for the change.

This test has often been described as a lenient approach for assessing
added subject-matter, and it has been criticised in a number of Decisions
since it was first described in T 331/87.

Decision

The Board in T 1852/13 reviewed the history of the 'essentiality test', as
well as the criticism resulting from its application.

The Board ultimately found that the test is in conflict with the Gold
Standard for assessing added subject-matter following claim amendments. The
Gold Standard (from G2/10) states that any amendment must lead to
subject-matter that the skilled person would derive directly and
unambiguously, using his common general knowledge, from the
application-as-filed.

An inconsistency between the two tests arose from whether the application
disclosed the non-essentiality of the feature (Gold Standard) or simply
didn't disclose the essentiality of the feature (essentiality test). The
Board concluded that the Gold Standard is a superior test, and stated that
"the essentiality test should not be used anymore".

Conclusion

Due to the outcome of the case being the same no matter which test was
applied, the Board refused to refer any questions to the Enlarged Board of
Appeal.

Thus, although this Decision provides a significant blow to the validity of
the 'essentiality test', it has not provided a definitive answer as to
whether the test is out-dated and irrelevant.